The extraction results are summarized in Table 1. Sodium thiosulfate
produced the highest yield of dried carbohydrate compounds
from the extracts and at the highest concentration. After
bleaching, the pulp obtained from the sodium thiosulfate extraction
gave the highest breaking lengths, as shown in Table 2. The
sample, water-2, gave the lowest brightness. In fact, for the
water-2 case, repeated bleaching did not improve its brightness
(H2O2 stage). As previously observed (Seo et al., 2010), red algae
pulp showed higher opacity than wood pulp (Table 2).
Bleached wood chemical pulp usually gives opacities of approximately
70–80% for softwood and 80–85% for hardwood, at a basis
weight of 60 g/m2
. More than 10% higher ISO opacity for an equivalent
mass was obtained with red algae pulp. Table 3 shows the
chemical composition of the soluble carbohydrates in the extracts